The present invention relates to a process for manufacturing forms of packaging having good barrier properties against the passage of water vapour and gases, featuring recesses of a first film-shaped material as containers to accommodate contents, where the film-shaped material is shape-formed to create the containers, cut into individual packaging, the contents added to the containers, and the filled packaging closed off by a second film-shaped material having good barrier properties against passage of water vapour and gases. Also within the scope of the invention is a device suitable for carrying out the process.
It is known to manufacture forms of packaging from a film-shaped material having shape-formed containers, such as the base parts of blister packsxe2x80x94also known as push-through packsxe2x80x94or other packaging containers such as menu-dishes and the like made e.g. by deep drawing, stretch drawing or thermoforming. The packaging forms may be made from thermoplastic materials or from film composites or laminates such as aluminium foil laminated onto plastic film, or extrusion coated layers of thermoplastic materials.
In order to achieve a form of packaging with good barrier properties against water vapour and gasesxe2x80x94a so-called barrier layerxe2x80x94it is known to choose film-shaped or strip-shaped material which already exhibits the desired barrier properties for manufacturing the packaging. Starting materials are materials with organic barrier properties such as e.g. polyvinylidenchloride (PVDC) or a fluorine-containing polymer which has become known under the name Aclar(copyright). Also known, as barrier layer for contents sensitive to oxygen, are polymers of ethylvinyl-alcohol. A film used in blister packs for tablets exhibits aluminium as barrier layer. Also known are plastic films whose barrier properties can be improved in some cases by depositing ceramic coatings or layers of aluminium by vacuum thin-film deposition using PVD (physical vapour deposition) or CVD (chemical vapour deposition) methods. Known for example are plastic films having a 10 to 200 nm thick layer of Al, Al2O3 or SiOx, where x is a number between 0.9 and 2.
The above mentioned films with barrier properties suffer from substantial disadvantages. For example Aclar(copyright) and PVDC both contain chlorine, Aclar(copyright) also contains fluorine, for which reason the disposal of both materials is difficult. Furthermore, both materials are relatively expensive. EVOH is only suitable for foodstuffs as it does not exhibit good barrier properties against water vapour. Laminates having aluminium as barrier layer exhibit excellent barrier properties, but they are relatively expensive and exhibit limited formability.
A further disadvantage is the absence of light transparency, which is increasingly in demand in blister packs for tablets.
The object of the invention is therefore to provide a process for manufacturing packaging of the kind described at the start which does not exhibit the disadvantages of the state-of the-art processes. With the process in question it should be possible to produce different kinds of barrier properties in a simple and cost favourable manner.
That objective is achieved by way of the invention in which the barrier properties of the packaging against passage of water vapour and gases are created after shaping the container, this by means of vacuum coating with materials that exhibit the desired barrier properties.
The process according to the invention enables packaging forms to be manufactured from a large number of starting materials. Useful in particular are transparent plastics with good formability properties such as polyethylene (PE), polypropylene (PP), cyclo-olefine copolymers (COC), polyvinylchloride (PVC), polyethyleneterephthalate (PET), polyamide (PA) and laminates manufactured out of the above mentioned materials.
The coating of the packaging may be carried out on the inside or the outside of the container. Coating the outside permits e.g. the barrier layer to be deposited on the already filled and sealed pack.
The coating may be deposited by sputtering, vapour deposition or by plasma-polymerisation. A useful coating is comprised of metals or metal oxides. Preferred is sputtering metals, in particular aluminium or metal oxides, in particular SiOx, where x is a number between 0.9 and 2, or plasma-polymerisation of silicon oxides, preferably starting from organosilanes such as hexamethyldisiloxane (HMDSO) or tetramethyldisiloxane (TMDSO). Also possible however is plasma-polymerisation of highly cross-linked carbohydrate layers, e.g. starting from methane, ethylene or acetylene.
In a particularly preferred version of the process according to the invention the production of the packaging, the coating and if desired the filling and closing are carried out in line.
A device which is suitable for carrying out the process according to the invention exhibits, besides a shape-forming station for shaping the containers out of the film-shaped material and a cutting station for cutting the packaging out of the shape-formed, film-shaped material, a vacuum coating station for coating the packaging.
A preferred version of the device according to the invention is such that the vacuum coating station exhibits a turntable for transporting the packaging within the station. Usefully, the turntable of the vacuum coating station can be loaded with the packaging to be coated via a gas lock, and the coated packaging removed via the gas lock.
The process according to the invention and the use of the device are particularly suitable for manufacturing blister packs with good barrier properties against passage of water vapour and gases whereby, depending on the choice of materials to be coated, light transparency or opacity can be achieved.